Source Diffractive
The source diffractive calculates the wavefront in an aperture using Fraunhofer diffraction theory, this wavefront is then used to provide a set of direction cosines for the rays it generates. The spatial distribution of ray starting coordinates is randomly assigned within the aperture. All rays are assigned the same intensity value. The sum of these values is normalized to the power on the source, which is defined by parameter 3. The aperture is defined by a UDA file which is selected in the Type tab of the Object Properties window; any scaling of the aperture is also defined here.
The parameters used to define this source are:
| Parameter # | Definition |
| 1-5 | See "Parameters common to all source objects" . |
| 6 | Sampling: Integer values that define the sampling. An input of 1 corresponds to 32x32 points in the grid up to a maximum input of 9, which corresponds to 8192x8912 points. |
Fraunhofer Diffraction
For a short description on Fraunhofer diffraction theory see Fraunhofer Diffraction. For a more detailed discussion of this source, see the Knowledgebase article The Source Diffractive object. For important information about sampling issues see "Discussion of the FFT method and sampling issues" .
Use with LightningTrace
This source type is not supported by LightningTrace.
Comment on pixel size when objects are detectors
For most objects, you can edit the pixel size by clicking Object Property > Draw > Drawing Resolution. For a STEP/IGES/SAT CAD file, the pixel size is controlled by the Chord Tolerance parameter in Object Properties > CAD (see "Chord Tolerance" for more information). For an STL file, the pixels are determined by the triangles defined in the file and cannot be changed.
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